1. Field of the Disclosure
This specification relates to a mobile terminal having a smart measuring tape, capable of measuring a length of a subject, which is captured or has been captured through a camera, and a length measuring method thereof.
2. Background of the Disclosure
Terminals may be generally classified as mobile/portable terminals or stationary terminals. Mobile terminals may also be classified as handheld terminals or vehicle mounted terminals. Mobile terminals have become increasingly more functional. Examples of such functions include data and voice communications, capturing images and video via a camera, recording audio, playing music files via a speaker system, and displaying images and video on a display.
Some mobile terminals include additional functionality which supports game playing, while other terminals are configured as multimedia players. More recently, mobile terminals have been configured to receive broadcast and multicast signals which permit viewing of content such as videos and television programs. As it becomes multifunctional, a mobile terminal can capture still images or moving images, play music or video files, play games, receive broadcast and the like, so as to be implemented as an integrated multimedia player.
In general, an auto focus (AF) function is used upon capturing a subject using a camera. The distance is measured from the camera to the subject upon carrying out the AF function. The distance measurement up to the subject may be performed according to a method using infrared rays or supersonic waves or a through-the-lens (TTL) method.
The method of measuring the distance using the supersonic waves calculates the distance by measuring a time which is taken for supersonic wave emitted from a supersonic generator of the mobile terminal to come back to the mobile terminal by being reflected from an object (or subject). Further, the method of measuring the distance using infrared rays calculates the distance by measuring a strength or a time of infrared ray which comes back by being reflected from an object.
Further, the TTL method brings a camera lens into focus on an object by analyzing an image obtained through a CCD/CMOS image sensor, and calculates the distance up to the object based on a position of a lens in the focus-on state. However, the method using the infrared rays or ultrasonic waves has a limit of the distance that the infrared ray or the ultrasonic wave can reach, so as to cause a difficulty in measuring the distance up to a subject located at a far distance. Also, in this method, an accurate adjustment of focus on an object which is very close to a camera lens is hardly executed due to parallax.
Further, the TTL method can adjust the focus even on an object located at a far distance or an object very close to the camera lens, without any trouble. However, the CCD/CMOS image sensor cannot accurately detect contrast (details) of an object, such as an object (a blue sky, a monochromic wall, etc.) with a low contrast ratio, an object located at a place with less light, an object with high reflectivity, and the like, which results in a difficulty of distance measurement.
Therefore, a mobile terminal which measures the distance according to the related art method using the infrared rays or ultrasonic waves and the TTL method cannot measure an accurate distance, and thereby fails to perform an accurate AF function using those methods. Also, in the related art, the distance measurement technology is merely applied to a limited function, such as the auto focus, but fails to provide various functions and user interfaces (UIs) in association with a capturing scene of a camera or an object online.